Back side illumination image sensors and electronic device including the same

ABSTRACT

In some example embodiments, a back side illumination (BSI) image sensor may include a pixel configured to generate electrical signals in response to light incident on a back side of a substrate. In some example embodiments, the pixel includes, a photodiode, a device isolation film adjacent to the photodiode, a dark current suppression layer above the photodiode, a light shield grid above the photodiode and including an opening area of 1 to 15% of an area of the pixel, a light shielding filter layer above the light shield grid, a planarization layer above the light shielding filter layer, a lens above the planarization layer, and/or an anti-reflective film between the photodiode and the lens.

CROSS-REFERENCE TO THE RELATED APPLICATIONS

This U.S. nonprovisional patent application is a continuation of U.S.patent application Ser. No. 16/775,481, filed on Jan. 29, 2020, which isa continuation of U.S. patent application Ser. No. 16/451,561, filed onJun. 25, 2019, which claims priority under 35 U.S.C. § 119 to and thebenefit of Korean Patent Application No. 10-2018-0167379, filed on Dec.21, 2018, in the Korean Intellectual Property Office (KIPO), thedisclosure of each of which are incorporated herein by reference in itsentirety.

BACKGROUND 1. Field

Some example embodiments of some inventive concepts relate to backsideillumination (BSI) image sensors and/or electronic devices including thesame.

2. Description of Related Art

Image sensors are devices that convert light into electrical signals.With the recent development of computer industry and communicationindustry, the image sensors having improved performance may be utilizedin various devices such as camcorders, game machines, digital cameras,display devices, mobile phones (e.g., smartphones), and the like. Frontside illumination (FSI) image sensors may exhibit disadvantages, such asa decrease in light-receiving efficiency due to an arrangement of wiringabove a photodiode. Back side illumination (BSI) image sensors, whereinthe wiring of the photodiode is below the photodiode, may provideimproved light-receiving efficiency as compared with FSI image sensors.

SUMMARY

A back side illumination image sensor according to some exampleembodiments of some inventive concepts includes a pixel configured togenerate electrical signals in response to incident light. The pixelcomprises a photodiode, a device isolation film adjacent to thephotodiode, a dark current suppression layer above the photodiode, alight shield grid above the photodiode and including an opening area of1 to 15% of an area of the pixel, a light shielding filter layer abovethe light shield grid, a planarization layer above the light shieldingfilter layer, a lens above the planarization layer, and ananti-reflective film between the photodiode and the lens.

A back side illumination image sensor according to some exampleembodiments of some inventive concepts includes a plurality of pixelsconfigured to generate electrical signals in response to light incidenton a back side of a substrate, and a plurality of readout circuitsconfigured to read the electrical signals of the plurality of pixels.Each pixel of the plurality of pixels comprises a photodiode, a darkcurrent suppression layer above the photodiode, a light shield gridabove the photodiode and including an opening area that is aligned to acentral portion of the photodiode, a planarization layer above the lightshield grid, a lens above the planarization layer, and ananti-reflective film between the photodiode and the lens.

A back side illumination image sensor according to some exampleembodiments of some inventive concepts includes a plurality of pixelsconfigured to generate electrical signals in response to light incidenton a back side of a substrate, and a plurality of readout circuitsconfigured to read the electrical signals of the plurality of pixels.Each pixel of the plurality of pixels comprises a photodiode, a lightshield grid above the photodiode and including an opening area of 1 to15% of an area of the pixel, a planarization layer on the light shieldgrid, a lens above the planarization layer, an anti-reflective filmbetween the photodiode and the lens, and a display panel is above thelens.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating an electronic device including a BSI imagesensor according to some example embodiments of some inventive concepts.

FIG. 2 is a circuit diagram of a unit pixel of an image sensor accordingto some example embodiments.

FIG. 3A is a view illustrating an image sensor according to some exampleembodiments of some inventive concepts, in which an anti-reflective filmand a dark current suppression layer are disposed between a light shieldgrid and a photodiode.

FIG. 3B is a view illustrating a device isolation film of a pixel shownin FIG. 3A according to some example embodiments.

FIG. 3C is a view illustrating a light shielding filter layer of thepixel shown in FIG. 3B according to some example embodiments.

FIG. 3D is a view illustrating a device isolation film and a darkcurrent suppression layer according to some example embodiments.

FIGS. 4A and 4B are views illustrating a plurality of films laminated toform an anti-reflective film according to some example embodiments.

FIGS. 5A and 5B are views illustrating a light shielding grid of animage sensor according to some example embodiments.

FIG. 6A is a view illustrating a pixel of an image sensor according tosome example embodiments of some inventive concepts, in which ananti-reflective film is disposed between a light shield grid and a lightshielding filter layer.

FIG. 6B is a view illustrating a device isolation film is disposed inthe pixel shown in FIG. 6A according to some example embodiments.

FIG. 7A is a view illustrating a pixel of an image sensor according tosome example embodiments of some inventive concepts in which ananti-reflective film is disposed between a light shielding filter layerand a planarization layer.

FIG. 7B is a view illustrating a case in which a device isolation filmis disposed in the pixel shown in FIG. 7A according to some exampleembodiments.

FIG. 8A is a view illustrating a pixel of an image sensor according tosome example embodiments of some inventive concepts in which ananti-reflective film is disposed between a planarization layer and alens.

FIG. 8B is a view illustrating a device isolation film of the pixelshown in FIG. 8A according to some example embodiments.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 1 is a view illustrating an electronic device including a BSI imagesensor according to some example embodiments of some inventive concepts.

Referring to FIG. 1 , an electronic device 10 according to some exampleembodiments of some inventive concepts may include an image sensor 100and a display module 200. The display module 200 that is configured todisplay images may be disposed on an upper side, and the image sensor100 may be arranged under the display module 200. The display module 200may include an organic light emitting diode (OLED) panel 210 as adisplay panel configured to display the images. The display module 200may include a touch panel 220 configured to sense a user's touch. Thetouch panel 220 may be disposed above the OLED panel 210. The displaymodule 200 may include a protection film 230 disposed above the touchpanel 220 and a cushion 240 configured to buffer an impact applied whentouched.

In some example embodiments, an OLED panel 210 may be configured todisplay the image on the basis of an input image signal and may displaythe image by self-emitting without a backlight. Some OLED panels 210 mayhave a low thickness in a height direction as no backlight is involved.As used herein, “height direction” means a direction that issubstantially orthogonal to a planar surface of the substrate. Sometouch panels 220 may utilize sensors provided on a surface thereof todetect the touch input by converting a change in states of the sensorssuch as a change in pressure, a change in capacitance, a change in lightamount, and the like applied to the surface into an electric signal.FIG. 1 includes an example embodiment in which the OLED panel 210 isapplied as the display panel is shown. Some example embodiments of someinventive concepts may not be limited thereto; for example, in someexample embodiments, as an alternative to an OLED panel 210, other typesof display panels through which light may be transmitted may beincluded.

Some example embodiments may include touch panels 220 that areimplemented as a resistive type, a capacitive type, a surface acousticwave type, or an infrared type. In some example embodiments, theprotection film 230 may be disposed on a front surface of the touchpanel 220 and/or may be formed thereon so as to have a certain (e.g.,desired and/or selected) thickness in a height direction to protect thefront surface of the touch panel 220. In some example embodiments, aprotection film 230 may prevent or reduce light incident from theoutside of the touch panel 220 from being reflected.

In some example embodiments, an image sensor 100 may include a pluralityof pixels 110 and/or a printed circuit board (PCB) 120 on which aprocessor and/or a driving circuit, which may be configured to drive theplurality of pixels 110, are disposed. In some example embodiments, eachof the plurality of pixels 110 may be formed in the form of a chip,and/or the plurality of pixels 110 in a chip form may be disposed abovethe PCB 120. That is, in some example embodiments, unit pixels in thechip form may be gathered to of a pixel array, and/or the pixel arraymay be disposed on the PCB 120.

In some example embodiments, an image sensor 100 may include acomplementary metal oxide semiconductor (CMOS) image sensor (CIS). Insome example embodiments, the image sensor 100 may be configured toconvert the received light into the electrical signal, to generate asensing signal when the image sensor 100 is touched by a finger of auser, and/or to output the sensing signal to the processor. In someexample embodiments, a processor may generate a fingerprint image basedon the sensing signal received at the image sensor 100.

The electronic device 10 according to some example embodiments of someinventive concepts may include communication functions. In some exampleembodiments, the electronic device 10 may include one or more of asmartphone, a tablet personal computer (PC), a mobile phone, a wearabledevice (e.g., a smart watch), an e-book, a netbook computer, a personaldigital assistant (PDA), a portable multimedia player (PMP), a mobilemedical instrument, and/or a digital camera.

FIG. 2 is a circuit diagram of the unit pixel of an image sensoraccording to some example embodiments.

In the circuit diagram of FIG. 2 , each of the plurality of pixels 110may include a photodiode PD, which is a photosensitive device, and/or aplurality of transistors TX, RX, DX, and SX as a readout circuit. Insome example embodiments, the readout circuit may drive the photodiodePD and/or read an electrical signal generated by the photodiode PD. Insome example embodiments, the readout circuit may include a transfertransistor TX, a driving transistor DX, a selection transistor SX,and/or a reset transistor RX.

In some example embodiments, photocharges generated by the photodiode PDmay be output to a first node N1 (for example, a floating diffusionnode) through the transfer transistor TX.

In some such example embodiments, while a transfer control signal TG isa first level (e.g., a logical high level), a transfer transistor TX maybe turned on. In some example embodiments, while a transfer transistorTX is turned on, photocharges generated by the photodiode PD may beoutput to a first node N1 through a transfer transistor TX.

In some example embodiments, a driving transistor DX may operate as asource follower buffer amplifier. For example, a driving transistor DXmay amplify a signal corresponding to the charges stored in the firstnode N1.

In some example embodiments, a selection transistor SX may be turned onin response to a selection signal SEL. While the selection transistor SXis turned on, a signal amplified by the driving transistor DX may betransmitted to a column line COL.

In some example embodiments, a reset transistor RX may be turned on inresponse to a reset signal RS. While the reset transistor RX is turnedon, the charges stored in the first node N1 may be discharged.

FIG. 2 illustrates a pixel 110 including one photodiode PD and four MOStransistors TX, RS, DX, and SX according to some example embodiments.Example embodiments of some inventive concepts may not be limitedthereto. For example, in some other example embodiments, a pixel mayinclude one photodiode PD and three or fewer MOS transistors. In stillother example embodiments, a pixel may include one photodiode PD andfive or more MOS transistors.

FIG. 3A is a view illustrating an image sensor according to some exampleembodiments of some inventive concepts, in which an anti-reflective filmand a dark current suppression layer are disposed between a light shieldgrid and a photodiode. FIG. 3B is a view illustrating a device isolationfilm of the pixel shown in FIG. 3A according to some exampleembodiments.

Referring to FIGS. 1 and 3A, a pixel 110 of a BSI image sensor 100 isshown. In some example embodiments, each of the plurality of pixels 110may include a dark current suppression layer 111, a photodiode 112, ananti-reflective film 113, a light shield grid 114, a planarization layer115, and/or a lens 116.

As shown in FIG. 3B, a deep trench isolation (DTI) having a certain(e.g., desired and/or selected) depth may be disposed between thepixels, and/or the dark current suppression layer 111 may be disposedabove the photodiode 112, in some example embodiments.

In some example embodiments, the DTI may be configured to reduceinterference between the pixels 110 and/or may be disposed to surroundthe pixel 110. For example, the DTI may be formed by forming a trench ona back side of a silicon substrate and then burying an insulating filmin the trench. In some example embodiments, the DTI may be formed tohave a depth of 1 μm to 5 μm, e.g., as a deep trench isolation layerincluding an insulating material. In some example embodiments, the DTImay include an insulating material having a refractive index smallerthan that of the silicon substrate to prevent or reduce light incidenton each pixel 110 from passing over another adjacent pixel 110. In someexample embodiments, interference of the light between adjacent pixels110 may be prevented and/or reduced by a DTI that is deeply formed inthe substrate.

In some example embodiments, a photodiode 112 may be configured toreceive the light to generate photocharges and/or may be formed on theback side of the silicon substrate. For example, a plurality oftransistors (see FIG. 2 ) may be disposed as spaced apart from eachother on the same layer as the photodiode 112 and/or may be disposedunder the photodiode 112. In some example embodiments, wiringsconnecting the photodiode 112 to the transistors may be disposed underthe photodiode 112 (a front side of the silicon substrate). During amanufacturing process of an image sensor 100 according to some exampleembodiments, a portion of a back side of the silicon substrate may becut to a thickness in a height direction (for example, 3 μm) throughwhich light may be transmitted, and/or a DTI and photodiode 112 may beformed on the back side of the silicon substrate; while the transistorsand the wirings may be formed on the front side of the siliconsubstrate. In some example embodiments, the dark current suppressionlayer 111 may be disposed above the photodiode 112. In some exampleembodiments, the anti-reflective film 113 may be disposed above the darkcurrent suppression layer 111; the light shield grid 114 may be disposedon the anti-reflective film 113; the planarization layer 115 may bedisposed on the light shield grid 114; and/or the lens 116 may bedisposed on the planarization layer 115. Some example embodiments ofsome inventive concepts may not be limited thereto; for example, in someexample embodiments, a protection film may be disposed to cover thelight shield grid 114.

In some example embodiments, a lens 116 may be formed in a cylindricalshape or a hemispherical shape (e.g., in order to promote the collectionof incident light at one point). Light may be incident on the photodiode112 through the back side of the silicon substrate. In the BSI imagesensor 100, the wirings are disposed under the photodiode 112 so thatthe incident light is not disturbed by the wirings. Accordingly, in someexample embodiments, a BSI image sensor 100 may be configured to collectlight at a wide angle into the photodiode 112.

In some example embodiments, a pixel 110 may be configured to generate aphotocurrent by photoelectric conversion while the light is incidentthereon. A dark current, involving a constant amount of current that maybe generated by the pixel 110 even while the light is not incident, mayoccur. In some example embodiments, dark current may degrade theperformance of some image sensors, and it may be necessary, desirable,and/or advantageous to eliminate, prevent, reduce, and/or suppress thedark current. In some example embodiments of some inventive concepts,the dark current suppression layer 111 may be disposed above thephotodiode 112.

Some example embodiments may include a dark current suppression layer111 that is disposed on an upper surface of the silicon substrate, asshown in FIG. 3A.

Some example embodiments, such as shown in FIG. 3B, may include a darkcurrent suppression layer 111 that is integrally formed with the DTIand/or disposed on a front side of the silicon substrate.

As one example, the DTI is formed on the back side of the siliconsubstrate, and then the dark current suppression layer 111 may bedisposed above the photodiode 112 and the DTI.

In some example embodiments, formation of a dark current suppressionlayer 111 may include laminating a plurality of layers having a fixednegative charge. For example, each of the plurality of layers of thedark current suppression layer 111 may include one material or acombination of two or more materials selected from a group includingaluminum oxide (AlO), tantalum oxide (TaO), hafnium oxide (HfO),zirconium oxide (ZrO), and lanthanum oxide (LaO).

In some example embodiments, formation of the dark current suppressionlayer 111 may include laminating two layers. For example, a dark currentsuppression layer 111 may include a lamination of an aluminum oxide(AlO) layer and a tantalum oxide (TaO) layer, and/or may be disposedabove the photodiode 112. Some example embodiments may include a darkcurrent suppression layer 111 that is disposed on the front side of thesilicon substrate and/or that overlaps the photodiode 112. In someexample embodiments, a dark current suppression layer 111 may include analuminum oxide (AlO) layer that is disposed on a lower side and/or atantalum oxide (TaO) layer that is disposed on an upper side. Someexample embodiments of some inventive concepts may not be limitedthereto; for example, some other example embodiments may include a darkcurrent suppression layer 111 including a tantalum oxide (TaO) layerthat is disposed on the lower side and/or an aluminum oxide (AlO) layerthat is disposed on the upper side. Some example embodiments may includea dark current suppression layer 111 including an aluminum oxide (AlO)layer and a tantalum oxide (TaO) layer, each having a same or similarthickness in a height direction as other layers of the dark currentsuppression layer 111. Some example embodiments of some inventiveconcepts may not be limited thereto; for example, some other exampleembodiments may include a dark current suppression layer including analuminum oxide (AlO) layer and a tantalum oxide (TaO) layer that havedifferent thicknesses in a height direction.

In some example embodiments, the dark current suppression layer 111 maybe formed by laminating two layers. For example, a dark currentsuppression layer 111 may be formed by laminating an aluminum oxide(AlO) layer and a hafnium oxide (HfO) layer above the photodiode 112.Some example embodiments may include a dark current suppression layer111 that is disposed on the front side of the silicon substrate and/orthat overlaps the photodiode 112. Some example embodiments may include adark current suppression layer 111 including an aluminum oxide (AlO)layer that is disposed on the lower side and/or a hafnium oxide (HfO)layer that is disposed on the upper side. Some example embodiments ofsome inventive concepts may not be limited thereto; for example, someother example embodiments may include a dark current suppression layer111 including a hafnium oxide (HfO) layer that is disposed on the lowerside and/or an aluminum oxide (AlO) layer that is disposed on the upperside. Some example embodiments may include a dark current suppressionlayer 111 including an aluminum oxide (AlO) layer and a hafnium oxide(HfO) layer, each having a same or similar thickness in a heightdirection as other layers of the dark current suppression layer 111.Some example embodiments of some inventive concepts may not be notlimited thereto; for example, some other example embodiments may includea dark current suppression layer 111 including an aluminum oxide (AlO)layer and a hafnium oxide (HfO) layer that have different thicknesses ina height direction.

Some example embodiments may include a dark current suppression layer111 that is formed by laminating two layers. For example, a dark currentsuppression layer may include laminating a hafnium oxide (HfO) layerand/or a zirconium oxide (ZrO) layer, and/or may be disposed so as tooverlap the photodiode 112. In some example embodiments, a dark currentsuppression layer 111 may be formed by laminating a zirconium oxide(ZrO) layer and a lanthanum oxide (LaO) layer above the photodiode 112.

Some example embodiments may include a dark current suppression layer111 including a zirconium oxide (ZrO) layer that is disposed on thelower side and/or a lanthanum oxide (LaO) layer that is disposed on theupper side. Some example embodiments of some inventive concepts may notbe limited thereto; for example, some other example embodiments mayinclude a dark current suppression layer 111 including a lanthanum oxide(LaO) layer that is disposed on the lower side, and/or a zirconium oxide(ZrO) layer that is disposed on the upper side. Some example embodimentsmay include a dark current suppression layer 111 including a zirconiumoxide (ZrO) layer and a lanthanum oxide (LaO) layer, each having a sameor similar thickness in a height direction as other layers of the darkcurrent suppression layer 111. Some example embodiments of someinventive concepts may not be limited thereto; for example, some otherexample embodiments may include a dark current suppression layer 111including a zirconium oxide (ZrO) layer and a lanthanum oxide (LaO)layer that have different thicknesses in a height direction.

Some example embodiments may include, in addition to one or more of thecombinations of the layers described above, a first layer of the darkcurrent suppression layer 111 that includes at least one materialselected from among aluminum oxide (AlO), tantalum oxide (TaO), hafniumoxide (HfO), zirconium oxide (ZrO), and lanthanum oxide (LaO). Someexample embodiments may include a second layer of the dark currentsuppression layer 111 that includes a material other than the materialof the first layer. In some example embodiments, the dark currentsuppression layer 111 may be formed by laminating the second layer onthe first layer.

Some example embodiments may include a dark current suppression layer111 that is formed by laminating three layers. For example, a darkcurrent suppression layer 111 may be formed by laminating an aluminumoxide (AlO) layer, a tantalum oxide (TaO) layer, and a hafnium oxide(HfO) layer above the photodiode 112. In some example embodiments, analuminum oxide (AlO) layer may be included in a first layer in the darkcurrent suppression layer 111; a tantalum oxide (TaO) layer may beincluded in the second layer in the dark current suppression layer 111;and/or a hafnium oxide (HfO) layer may be included in a third layer inthe dark current suppression layer 111. Some example embodiments mayinclude a dark current suppression layer 111 including a first layerdisposed at the bottom; a second layer disposed on the first layer;and/or a third layer disposed on the second layer. Some exampleembodiments of some inventive concepts may not be limited thereto; forexample, some example embodiments may include a dark current suppressionlayer 111 in which the positions of the aluminum oxide (AlO) layer, thetantalum oxide (TaO) layer, and/or the hafnium oxide (HfO) layer areinterchanged. Some example embodiments may include a dark currentsuppression layer 111 including an aluminum oxide (AlO) layer, atantalum oxide (TaO) layer, and/or a hafnium oxide (HfO) layer, eachhaving a same or similar thickness in a height direction as other layersof the dark current suppression layer 111. Some example embodiments ofsome inventive concepts may not be limited thereto; for example, someother example embodiments may include a dark current suppression layer111 including an aluminum oxide (AlO) layer, a tantalum oxide (TaO)layer, and/or a hafnium oxide (HfO) layer that have differentthicknesses in a height direction.

Some example embodiments may include a dark current suppression layer111 that is formed by laminating three layers. For example, a darkcurrent suppression layer 111 may be formed by laminating a tantalumoxide (TaO) layer, a hafnium oxide (HfO) layer, and/or a zirconium oxide(ZrO) layer above the photodiode 112. In some example embodiments, atantalum oxide (TaO) layer may be disposed as a first layer in the darkcurrent suppression layer 111; a hafnium oxide (HfO) layer may bedisposed at the second layer in the dark current suppression layer 111;and/or a zirconium oxide (ZrO) layer may be disposed at the third layerin the dark current suppression layer 111. Some example embodiments mayinclude a dark current suppression layer 111 including a first layerdisposed at the bottom, a second layer disposed on the first layer,and/or a third layer disposed on the second layer. Some exampleembodiments of some inventive concepts may not be limited thereto; forexample, some example embodiments may include a dark current suppressionlayer 111 in which the positions of the tantalum oxide (TaO) layer, thehafnium oxide (HfO) layer, and the zirconium oxide (ZrO) layer areinterchanged. Some example embodiments may include a dark currentsuppression layer 111 including a tantalum oxide (TaO) layer, a hafniumoxide (HfO) layer, and/or a zirconium oxide (ZrO) layer, each having asame or similar thickness in a height direction as other layers of thedark current suppression layer 111. Some example embodiments of someinventive concepts may not be limited thereto; for example, some otherexample embodiments may include a dark current suppression layer 111including a tantalum oxide (TaO) layer, a hafnium oxide (HfO) layer,and/or a zirconium oxide (ZrO) layer that have different thicknesses ina height direction.

Some example embodiments may include a dark current suppression layer111 that is formed by laminating three layers. For example a darkcurrent suppression layer 111 may be formed by laminating a hafniumoxide (HfO) layer, a zirconium oxide (ZrO) layer, and/or a lanthanumoxide (LaO) layer above the photodiode 112. In some example embodiments,a hafnium oxide (HfO) layer may be included in the first layer in thedark current suppression layer 111; a zirconium oxide (ZrO) layer may beincluded in second layer in the dark current suppression layer 111;and/or a lanthanum oxide (LaO) layer may be included in the third layerin the dark current suppression layer 111. Some example embodiments mayinclude a dark current suppression layer 111 including a first layerdisposed at the bottom, a second layer disposed on the first layer,and/or a third layer disposed on the second layer. Some exampleembodiments of some inventive concepts may not be limited thereto; forexample, some example embodiments may include a dark current suppressionlayer 111 in which the positions of the hafnium oxide (HfO) layer, thezirconium oxide (ZrO) layer, and the lanthanum oxide (LaO) layer areinterchanged. Some example embodiments may include a dark currentsuppression layer 111 including a hafnium oxide (HfO) layer, a zirconiumoxide (ZrO) layer, and/or a lanthanum oxide (LaO) layer, each having asame or similar thickness in a height direction as other layers of thedark current suppression layer 111. Some example embodiments of someinventive concepts may not be limited thereto; for example, some otherexample embodiments may include a dark current suppression layer 111including a hafnium oxide (HfO) layer, a zirconium oxide (ZrO) layer,and/or a lanthanum oxide (LaO) layer that have different thicknesses ina height direction.

Some example embodiments may include, in addition to the combinations oflayers described above, a first layer of the dark current suppressionlayer 111 including one or more materials selected from aluminum oxide(AlO), tantalum oxide (TaO), hafnium oxide (HfO), zirconium oxide (ZrO),and lanthanum oxide (LaO). In some example embodiments, a second layerof the dark current suppression layer 111 may include a material otherthan the materials of the first layer, and/or a third layer of the darkcurrent suppression layer 111 may include a material other thanmaterials of the first layer and the second layer.

Some example embodiments may include a dark current suppression layer111 that is formed by laminating four layers. For example, a darkcurrent suppression layer 111 may be formed by laminating an aluminumoxide (AlO) layer, a tantalum oxide (TaO) layer, a hafnium oxide (HfO)layer, and/or a zirconium oxide (ZrO) layer above the photodiode 112.Some example embodiments may include an aluminum oxide (AlO) layerdisposed at the first layer in the dark current suppression layer 111; atantalum oxide (TaO) layer disposed at the second layer in the darkcurrent suppression layer 111; a hafnium oxide (HfO) layer disposed atthe third layer in the dark current suppression layer 111; and/or azirconium oxide (ZrO) layer disposed at a fourth layer in the darkcurrent suppression layer 111. Some example embodiments may include adark current suppression layer 111 including a first layer disposed atthe bottom, a second layer disposed on the first layer, a third layerdisposed on the second layer, and/or a fourth layer disposed on thethird layer. Some example embodiments of some inventive concepts may notbe limited thereto; for example, some example embodiments may include adark current suppression layer 111 in which the positions of thealuminum oxide (AlO) layer, the tantalum oxide (TaO) layer, the hafniumoxide (HfO) layer, and the zirconium oxide (ZrO) layer are interchanged.Some example embodiments may include a dark current suppression layer111 including an aluminum oxide (AlO) layer, a tantalum oxide (TaO)layer, a hafnium oxide (HfO) layer, and/or a zirconium oxide (ZrO)layer, each that having a same or similar thickness in a heightdirection as other layers of the dark current suppression layer 111.Some example embodiments of some inventive concepts may not be limitedthereto; for example, some other example embodiments may include analuminum oxide (AlO) layer, a tantalum oxide (TaO) layer, a hafniumoxide (HfO) layer, and a zirconium oxide (ZrO) layer may have differentthicknesses in the dark current suppression layer 111.

Some example embodiments may include dark current suppression layer 111that is formed by laminating four layers. For example, a dark currentsuppression layer 111 may be formed by laminating a hafnium oxide (HfO)layer, a tantalum oxide (TaO) layer, a zirconium oxide (ZrO) layer,and/or lanthanum oxide (LaO) layer above the photodiode 112. Someexample embodiments may include a tantalum oxide (TaO) layer included ina first layer in the dark current suppression layer 111; a hafnium oxide(HfO) layer included in a second layer in the dark current suppressionlayer 111; a zirconium oxide (ZrO) layer included in a third layer inthe dark current suppression layer 111; and/or a lanthanum oxide (LaO)layer included in a fourth layer in the dark current suppression layer111. Some example embodiments may include a dark current suppressionlayer 111 including a first layer disposed at the bottom, a second layerdisposed on the first layer, a third layer disposed on the second layer,and/or a fourth layer disposed on the third layer. Some exampleembodiments of some inventive concepts may not be limited thereto; forexample, some example embodiments may include a dark current suppressionlayer 111 in which the positions of the tantalum oxide (TaO) layer, thehafnium oxide (HfO) layer, the zirconium oxide (ZrO) layer, and thelanthanum oxide (LaO) layer are interchanged. Some example embodimentsmay include a dark current suppression layer 111 including a tantalumoxide (TaO) layer, a hafnium oxide (HfO) layer, a zirconium oxide (ZrO)layer, and/or a lanthanum oxide (LaO) layer, each having a same orsimilar thickness in a height direction as other layers of the darkcurrent suppression layer 111. Some example embodiments of someinventive concepts may not be limited thereto; for example, some otherexample embodiments may include a dark current suppression layer 111including a tantalum oxide (TaO) layer, a hafnium oxide (HfO) layer, azirconium oxide (ZrO) layer, and/or a lanthanum oxide (LaO) layer thathave different thicknesses in a height direction.

Some example embodiment may include dark current suppression layer 111that is formed by laminating four layers. For example, a dark currentsuppression layer 111 may be formed by laminating an aluminum oxide(AlO) layer, a tantalum oxide (TaO) layer, a hafnium oxide (HfO) layer,and a lanthanum oxide (LaO) layer above the photodiode 112. In someexample embodiments, an aluminum oxide (AlO) layer may be included in afirst layer in the dark current suppression layer 111; a tantalum oxide(TaO) layer may be included in a second layer in the dark currentsuppression layer 111; a hafnium oxide (HfO) layer included in a thirdlayer in the dark current suppression layer 111; and/or a lanthanumoxide (LaO) layer included in a fourth layer in the dark currentsuppression layer 111. Some example embodiments may include a darkcurrent suppression layer 111 including a first layer disposed at thebottom; a second layer disposed on the first layer; a third layerdisposed on the second layer; and/or a fourth layer disposed on thethird layer. Some example embodiments of some inventive concepts may notbe limited thereto; for example, some example embodiments may include adark current suppression layer 111 in which the positions of thealuminum oxide (AlO) layer, the tantalum oxide (TaO) layer, the hafniumoxide (HfO) layer, and/or the lanthanum oxide (LaO) layer areinterchanged. Some example embodiments may include a dark currentsuppression layer 111 including an aluminum oxide (AlO) layer, atantalum oxide (TaO) layer, a hafnium oxide (HfO) layer, and/or alanthanum oxide (LaO) layer, each having a same or similar thickness ina height direction as other layers of the dark current suppression layer111. Some example embodiments of some inventive concepts may not belimited thereto; for example, some other example embodiments may includea dark current suppression layer 111 including an aluminum oxide (AlO)layer, a tantalum oxide (TaO) layer, a hafnium oxide (HfO) layer, and/ora lanthanum oxide (LaO) layer that have different thicknesses in aheight direction.

In addition to the combinations of the layers described above, the firstlayer of the dark current suppression layer 111 may include one or morematerials selected from among aluminum oxide (AlO), tantalum oxide(TaO), hafnium oxide (HfO), zirconium oxide (ZrO), and lanthanum oxide(LaO). Some example embodiments may include a second layer of the darkcurrent suppression layer 111 that includes a material other than thematerials of a first layer; a third layer of the dark currentsuppression layer 111 that includes a material other than the materialsof the first layer and the second layer; and/or a fourth layer of thedark current suppression layer 111 that includes a material other thanthe materials of the first layer, the second layer, and the third layer.Some example embodiments may include a dark current suppression layer111 that is formed by sequentially laminating the first to fourthlayers.

Some example embodiments may include an anti-reflective film 113 that isdisposed on an upper surface of the dark current suppression layer 111.That is, some example embodiments may include an anti-reflective film113 that is disposed between the dark current suppression layer 111 andthe light shield grid 114.

FIG. 3C is a view illustrating a light shielding filter layer that isdisposed in the pixel shown in FIG. 3B in accordance with some exampleembodiments.

Referring to FIG. 3C, the light shield grid 114 may include a metalmaterial such as tungsten (W). The light incident on the pixel 110 maybe reflected from an upper surface of the light shield grid 114. If thelight reflected from the upper surface of the light shield grid 114 maybe viewed outside the pixel 110, then the quality of the image displayedon the OLED panel 210 may be degraded. Some example embodiments of someinventive concepts may prevent or reduce the light being reflected fromthe upper surface of the light shield grid 114 by including a lightshielding filter layer 117 disposed on the light shield grid 114.

In some example embodiments, the light shielding filter layer 117 is notformed above an opening area 114 a of the light shield grid 114, but maybe disposed so as to overlap the light shield grid 114. Theplanarization layer 115 may be disposed on the light shielding filterlayer 117, and the lens 116 may be disposed on the planarization layer115. In some example embodiments, the light shielding filter layer 117may include two or more color filters selected from a group comprising ared color filter, a green color filter, a blue color filter, a cyancolor filter, a magenta color filter, and a yellow color filter. In someexample embodiments, the two or more color filters may be laminated,and/or may be an organic material, which may be one material or acombination of two or more materials selected from a group consisting ofpolyacetylene, poly(p-phenylene), polythiophene,poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole,poly(p-phenylenesulfide), poly(p-phenylenevinylene), and polyaniline.

In some example embodiments, a planarization layer 115 may be disposedon the light shielding filter layer 117 to have a certain (e.g., desiredand/or selected) thickness in a height direction. In some exampleembodiments, a lens 116 that directs incident light toward thephotodiode 112 may be disposed above the planarization layer 115.

FIG. 3D is a view specifically illustrating an device isolation film anda dark current suppression layer in accordance with some exampleembodiments.

Referring to FIG. 3D, a dark current suppression layer 111 may beintegrally formed with the deep trench isolation (DTI) and/or may beformed on a front side of the silicon substrate. In some exampleembodiments, after forming a trench, the dark current suppression layer111 and the DTI, which include a plurality of layers, may be formed onthe front side of the silicon substrate and/or in the trench. In someexample embodiments, the dark current suppression layer 111 and/or theDTI may be formed by laminating a plurality of layers. For example, adark current suppression layer 111 and a DTI may be formed of fourlayers, where a first layer L1 includes one or more materials selectedfrom among aluminum oxide (AlO), tantalum oxide (TaO), hafnium oxide(HfO), zirconium oxide (ZrO), and lanthanum oxide (LaO); a second layerL2 includes a material other than the material of the first layer; athird layer L3 includes a material other than the materials of the firstlayer L1 and the second layer L2; and/or a fourth L4 includes a materialother than the material of the first to third layers L1, L2, and L3.Some example embodiments of some inventive concepts may not be limitedthereto; for example, in some other example embodiments, the darkcurrent suppression layer 111 and the DTI may have only two to threelayers, or may have five or more layers. In some example embodiments,the dark current suppression layer 111 and the DTI are integrallyformed, and the dark current suppression layer 111 and/or the DTI may beformed by laminating a plurality of layers having a fixed negativecharge.

FIGS. 4A and 4B are views illustrating a plurality of films arelaminated to form the anti-reflective film in accordance with someexample embodiments.

Referring to FIG. 4A, in the anti-reflective film 113, a plurality ofsub-films are laminated to prevent or reduce the reflection of thelight. In some example embodiments, the anti-reflective film 113 mayinclude a plurality of sub-films. For example, in FIGS. 4A and 4B, theanti-reflective film 113 is formed of four sub-films 113 a to 113 d.However, some example embodiments of some inventive concepts may not belimited thereto; for example, in some other example embodiments, theanti-reflective film 113 may be formed by overlapping and/or laminating10 to 40 sub-films.

In some example embodiments, all of the plurality of sub-films of theanti-reflective film 113 may have different refractive indices. Someexample embodiments of some inventive concepts may not be limitedthereto; for example, in some other example embodiments, some sub-filmsamong the plurality of sub-films of the anti-reflective film 113 mayhave a same or similar refractive index as other sub-films of theanti-reflective film 113.

In some example embodiments, a first sub-film 113 a having a firstrefractive index may be disposed at a lowermost layer of theanti-reflective film 113; a second sub-film 113 b having a secondrefractive index that is different from the first refractive index maybe disposed on the first sub-film 113 a; a third sub-film 113 c having athird refractive index that is different from the second refractiveindex may be disposed on the second sub-film 113 b; and/or a fourthsub-film 113 d having a fourth refractive index that is different fromthe third refractive index may be disposed on the third sub-film 113 c.Some example embodiments may further include a fifth sub-film, asixth-sub film, a seventh sub-film, an eighth-sub film, a ninthsub-film, and a tenth-sub film, each sub-film having a differentrefractive index than at least one of the other sub-films.

Some example embodiments may include an anti-reflective film 113including a second sub-film 113 b that has a greater refractive index(first refractive index<second refractive index) than a first sub-film113 a; a third sub-film 113 c that has a greater refractive index than asecond sub-film 113 b (second refractive index<third refractive index);and/or a fourth sub-film 113 d that has a greater refractive index thanthe third sub-film 113 c (third refractive index<fourth refractiveindex). That is, the refractive indices of the sub-layers of theanti-reflective film 113 may increase from a lower portion to an upperportion thereof. Additionally, a fifth sub-film, a sixth-sub film, aseventh sub-film, an eighth sub-film, a ninth sub-film, and/or a tenthsub-film may have refractive indices that increase from the lowerportion to the upper portion. Some other example embodiments may includean anti-reflective film 113 including a second sub-film 113 b that has alower refractive index than a first sub-film 113 a (first refractiveindex>second refractive index); a third sub-film 113 c that has a lowerrefractive index than the second sub-film 113 b (second refractiveindex>third refractive index); and/or a fourth sub-film 113 d that has alower refractive index than the third sub-film 113 c (third refractiveindex>fourth refractive index). That is, the refractive indices of thesub-layers of the anti-reflective film 113 may decrease from a lowerportion to an upper portion thereof. Additionally, a fifth sub-film, asixth sub-film, a seventh sub-film, an eighth sub-film, a ninthsub-film, and/or a tenth sub-film may have refractive indices thatdecrease from the lower portion to the upper portion.

In some example embodiments, each of the plurality of sub-films may havea refractive index within a range of 1.4 to 2.6. In some exampleembodiments, each of the plurality of sub-films of the anti-reflectivefilm 113 may have a same or similar thickness in a height direction asother sub-films of the anti-reflective film 113. In some exampleembodiments, each of the plurality of sub-films may have a thickness ina height direction that is within a range of 0.1 μm to 0.5 μm (1,000 Åto 5,000 Å). Some example embodiments of some inventive concepts may notbe limited thereto; for example, in some other example embodiments, theplurality of sub-films of the anti-reflective film 113 may havedifferent thicknesses in a height direction relative to other sub-films.For example, the plurality of sub-films may have different thicknessesin a height direction relative to other sub-films, where the thicknessin the height direction of each layer may be within a range of 0.1 μm to0.5 μm (1,000 Å to 5,000 Å).

Referring to FIG. 4B, in an anti-reflective film 113, differentsub-films may be alternately laminated to prevent the reflection of thelight in accordance with some example embodiments

Some example embodiments may include an anti-reflective film 113 that isformed by laminating 2 to 10 sub-film pairs, where each sub-film pairincludes a low refractive index film 113L and a high refractive indexfilm 113H. For example, an anti-reflective film 113 may include aplurality of layers in which the first sub-film 113L (low refractiveindex film) has a first refractive index, and the second sub-film 113H(high refractive index film) has a second refractive index that isgreater than the first refractive index, and/or where the layers arealternately laminated. In some example embodiments, the second sub-film113H (high refractive index film) may be disposed at the lowermost layerof the anti-reflective film 113, and/or the first sub-film 113L (lowrefractive index film) may be laminated on the second sub-film 113H(high refractive index film), and/or the first sub-film 113L (lowrefractive index film) and the second sub-film 113H (high refractiveindex film) may be alternately laminated. In some example embodiments, afirst sub-film 113L (low refractive index film) may be disposed at anuppermost layer of the anti-reflective film 113 and/or a second sub-film113H (high refractive index film) may be disposed at a lowermost layerof the anti-reflective film 113. Some example embodiments of someinventive concepts may not be limited thereto; for example, some otherexample embodiments may include a second sub-film 113H (high refractiveindex film) disposed at the uppermost layer of the anti-reflective film113 and/or a first sub-film 113L (low refractive index film) disposed atthe lowermost layer of the anti-reflective film 113.

Some example embodiments may include a plurality of first sub-films 113L(low refractive index film), each having a same or similar refractiveindex as other first sub-films 113L of the anti-reflective film 113. Insome example embodiments, each of the plurality of first sub-films 113L(low refractive index film) may have a refractive index within a rangeof 1.2 to 1.8. In some example embodiments, each sub-film of a pluralityof second sub-films 113H (high refractive index film) may have a same orsimilar refractive index as other second sub-films of the plurality ofsecond sub-films. In some example embodiments, each second sub-film 113H(high refractive index film) may have a refractive index within a rangeof 2.0 to 2.8.

In some example embodiments, a plurality of first sub-films 113L (lowrefractive index film) may have the same or similar thickness in aheight direction as other first sub-films of the plurality of firstsub-films. For example, each first sub-film of the plurality of firstsub-films 113L (low refractive index film) may be formed to a thicknessin a height direction that is within a range of 0.1 μm to 0.5 μm (1,000Å to 5,000 Å). In some example embodiments, each second sub-film of theplurality of second sub-films 113H (high refractive index film) may havea same or similar thickness in a height direction as other secondsub-films of the plurality of sub-films. For example, each secondsub-film of the plurality of second sub-films 113H (high refractiveindex film) may be formed to a thickness in a height direction that iswithin a range of 0.1 μm to 0.5 μm (1,000 Å to 5,000 Å). Some exampleembodiments of some inventive concepts may not be limited thereto; forexample, in some example embodiments, each of the plurality of firstsub-films 113L (low refractive index film) may have a differentthickness in a height direction relative to other sub-films. Forexample, in some other example embodiments, each first sub-film of theplurality of first sub-films 113L (low refractive index film) may have adifferent thickness in a height direction than other first sub-films ofthe plurality of first sub-films, where the thickness in the heightdirection of each sub-film is within a range of 0.1 μm to 0.5 μm (1,000Å to 5,000 Å). In some other example embodiments, each second sub-filmof the plurality of second sub-films 113H (high refractive index film)may have a different thickness in a height direction than other secondsub-films of the plurality of sub-films, where the thickness in a heightdirection of each second sub-film is within a range of 0.1 μm to 0.5 μm(1,000 Å to 5,000 Å).

As illustrated in FIG. 4B, some example embodiments may include ananti-reflective film 113 including two laminated pairs of low refractiveindex films and the high refractive index films. Some exampleembodiments of some inventive concepts may not be limited thereto; forexample, some example embodiments may include an anti-reflective film113 including one laminated pair or three to ten laminated pairs of lowrefractive index films and high refractive index films.

As shown in FIG. 5A, some example embodiments may include a light shieldgrid 114 having a grid having circular shaped opening areas.

As shown in FIG. 5B, some example embodiments may include a light shieldgrid 114 having a grid having rectangular shaped opening areas.

Some example embodiments may include a light shield grid 114 including ametal material such as tungsten (W). The image sensor 100 in someexample embodiments of some inventive concepts may be configured togenerate a fingerprint image, and the opening area 114 a of the lightshield grid 114 may be very small in a lateral direction. As usedherein, the term “lateral direction” means a direction that issubstantially parallel to a planar surface of the substrate. Someexample embodiments may include a transparent layer including atransparent material that is disposed in the opening area 114 a. In someexample embodiments, light may be guided to be incident on thephotodiode 112 by the opening area 114 a of the light shield grid 114,which may be aligned with a central portion of the pixel 110 and/or acentral portion of the photodiode 112. In some example embodiments,light may be incident on the photodiode 112 of each pixel withoutpassing over another pixel by the opening area 114 a that is alignedwith each pixel. Some example embodiments may include an opening area114 that is filled with the transparent layer including the transparentmaterial.

Some example embodiments may include opening areas 114 a of the lightshield grid 114, each having an area size that is within a range of 1 to15% of the total area size of each pixel 110. That is, in some exampleembodiments, each opening area 114 a of the light shield grid 114 may beopen by as much as the area of 1 to 15% of the total area of each pixel110. In some example embodiments, light that is incident on an area ofthe photodiode 112 through the opening area 114 a that is smaller thanthe area of the pixel 110. In some example embodiments, the opening area114 a of the light shield grid 114 may be very small, which mayaccurately position the light incident on the photodiode 112 of eachpixel and/or may prevent and/or reduce the incidence of light frompassing over another adjacent pixel.

In some example embodiments, dark current may be suppressed or reducedin the photodiode 112. For example, the light shield grid 114 may beconfigured to receive a voltage within a range of 0 V to −2 V, which maybe applied to the light shield grid 114 during operation. An applicationof a voltage within the range of 0V to −2V to the light shield grid 114including a metal material, dark current may be prevented or reducedduring operation of the photodiode 112.

Referring again to FIGS. 3A and 3B, some example embodiments may includea planarization layer 115 disposed on the light shield grid 114.Referring to FIG. 3C, some example embodiments may include aplanarization layer 115 disposed on the light shielding filter layer117. In some example embodiments, an upper surface of the device, onwhich the lens 116 is disposed, may be flattened by the planarizationlayer 115. Some example embodiments may include a planarization layer115 that includes one or more films that are selected from a groupconsisting of an oxide film, a nitride film, and an oxynitride film.Some example embodiments may include a planarization layer 115 thatincludes a plurality of films, including two or more films that areselected from a group consisting of the oxide film, the nitride film,and the oxynitride film are laminated.

In some example embodiments light generated in the OLED panel 210 may bereflected by a finger of a user and may be incident on each pixel 110 ofthe image sensor 100. For example, the light reflected by the finger maypass through the lens 116 and the planarization layer 115, and/or may beincident on the photodiode 112 after passing through the anti-reflectivefilm 113 through the opening area 114 a formed by the light shield grid114.

The BSI image sensor 100 in some example embodiments of some inventiveconcepts may prevent or reduce interference between the pixels bydisposing the DTI between some pixels (e.g., adjacent pixels). In someexample embodiments, dark current may be suppressed or reduced by a darkcurrent suppression layer 111 above the photodiode 112. In some exampleembodiments, light may be prevented or reduced from being reflected byan anti-reflective film 113 disposed above the photodiode 112, which maypromote light efficiency in some example embodiments. In some exampleembodiments, dark current may be suppressed or reduced by disposing adark current suppression layer 111 above the photodiode 112 and applyingvoltage within a range of 0V to −2V to the light shield grid 114 formedof a metal material.

FIG. 6A is a view illustrating a pixel of an image sensor according tosome example embodiments of some inventive concepts, in which ananti-reflective film is disposed between a light shield grid and a lightshielding filter layer. FIG. 6B is a view illustrating some exampleembodiments in which a device isolation film is disposed in the pixelshown in FIG. 6A. In describing a pixel 110 shown in FIGS. 6A and 6B,description of the same or similar configuration as the pixel 110 shownin FIGS. 3A to 3C may be omitted.

Referring to FIGS. 1 and 6A, the pixel 110 of a BSI image sensor 100 inaccordance with some example embodiments is shown. In some exampleembodiments, each pixel of the plurality of pixels 110 may include adark current suppression layer 111, a photodiode 112, an anti-reflectivefilm 113, a light shield grid 114, a planarization layer 115, a lightshielding filter layer 117, and/or a lens 116.

Some example embodiments may include a he photodiode 112 formed on asilicon substrate and configured to receive light and/or to generatephotocharges. For example, a plurality of transistors (see FIG. 2 ) maybe disposed on the same layer as the photodiode 112 to be spaced apartfrom each other and/or may be disposed under the photodiode 112. In someexample embodiments, wirings connecting one or more photodiodes 112 toone or more transistors may be disposed under the one or morephotodiodes 112. In some example embodiments, during a manufacturingprocess of the image sensor 100, a portion of a back side of the siliconsubstrate may be cut to a thickness in a height direction (for example,3 μm) through which light may be transmitted, and/or a deep trenchisolation (DTI) and/or the photodiode 112 may be formed on the back sideof the silicon substrate. In some example embodiments, the transistorsand the wirings are formed on a front side of the silicon substrate. Insome example embodiments, a dark current suppression layer 111 may bedisposed above a photodiode 112; a light shield grid 114 may be disposedabove the dark current suppression layer 111; an anti-reflective film113 may be disposed on the light shield grid 114; a light shieldingfilter layer 117 may be disposed on the anti-reflective film 113; aplanarization layer 115 may be disposed on the light shielding filterlayer 117; and/or a lens 116 may be disposed on the planarization layer115. Some example embodiments of some inventive concepts may not belimited thereto; for example, in some other example embodiments, aprotection film may be disposed to cover the light shield grid 114.

In some example embodiments, dark current may degrade the performance ofsome image sensor, and it may be necessary, desirable, and/oradvantageous to eliminate, prevent, reduce, and/or suppress darkcurrent. Some example embodiments of some inventive concepts may includea dark current suppression layer 111 that is disposed above thephotodiode 112. As one example, the dark current suppression layer 111may be disposed on an upper side of the silicon substrate, as shown inFIG. 6A.

As shown in FIG. 6B, in some example embodiments, a DTI having a certain(e.g., desired and/or selected) depth may be disposed between somepixels (e.g., adjacent pixels), and/or a dark current suppression layer111 may be disposed above the photodiode 112. Some example embodimentsmay include a DTI that prevents or reduces interference between somepixels (such as adjacent pixels) and/or that may be disposed to surroundeach pixel. Some example embodiments may include a DTI that is formed byforming a trench on the back side of the silicon substrate and thenburying an insulating film in the trench. Some example embodiments mayinclude a DTI that has a depth in a height direction of 1 μm to 5 μm.Some example embodiments may include a DTI that includes a deep trenchisolation layer including an insulating material, which may have arefractive index that is smaller than the refractive index of thesilicon substrate, and may therefore prevent or reduce light incident oneach pixel from passing over another adjacent pixel. In some exampleembodiments, interference of light between adjacent pixels may beprevented or reduced by forming the DTI deep in the substrate in aheight direction.

Some example embodiments may include a DTI that is disposed on a backside of the silicon substrate and/or a dark current suppression layer111 that is disposed above the photodiode 112 and/or the DTI. Someexample embodiments may include a dark current suppression layer 111 ona front side of the silicon substrate. In some example embodiments, darkcurrent may be prevented or reduced in the photodiode 112 by applying avoltage within a range of 0V to −2V to the light shield grid 114 and/orthe dark current suppression layer 111.

Some example embodiments may include a dark current suppression layer111 that includes a plurality of laminated layers respectively having afixed negative charge. In some example embodiments, each layer of theplurality of layers of the dark current suppression layer 111 mayinclude one material or a combination of two or more materials selectedfrom a group comprising aluminum oxide (AlO), tantalum oxide (TaO),hafnium oxide (HfO), zirconium oxide (ZrO), and lanthanum oxide (LaO).

As shown in FIG. 3B, some example embodiments may include a dark currentsuppression layer 111 that is integrally formed with the DTI. Someexample embodiments may include a dark current suppression layer 111 ona front side of the silicon substrate. For example, after a trench isformed, a dark current suppression layer 111 and a DTI, each including aplurality of layers, may be formed on the front side of the siliconsubstrate and/or the trench. Some example embodiments may include a darkcurrent suppression layer 111 and/or a DTI that include a plurality oflaminated layers.

Some example embodiments may include an anti-reflective film 113 that isdisposed on the light shield grid 114. Some example embodiments mayinclude an anti-reflective film 113 that is disposed between the lightshield grid 114 and the light shielding filter layer 117.

Some example embodiments may include an anti-reflective film 113including a plurality of laminated sub-films, which may prevent orreduce the reflection of the light. Some example embodiments may includean anti-reflective film 113 including a plurality of sub-films. As shownin FIGS. 4A and 4B, some example embodiments may include ananti-reflective film 113 that includes four sub-films 113 a to 113 d.However, some example embodiments of some inventive concepts may not belimited thereto; for example, some other example embodiments may includean anti-reflective film 113 including 10 to 40 overlapping sub-films. Insome example embodiments, some or all of the sub-films of the of theplurality of sub-films of the anti-reflective film 113 may have arefractive index that is different than the refractive indices of othersub-films of the plurality of sub-films. Some example embodiments ofsome inventive concepts may not be limited thereto; for example, in someexample embodiments, some sub-films among the plurality of sub-films ofthe anti-reflective film 113 may have a refractive index that is thesame or similar to the refractive indices of other sub-films of theanti-reflective film 113.

Some example embodiments of some inventive concepts may prevent orreduce light from being reflected from an upper surface of the lightshield grid 114 by a light shielding filter layer 117 on ananti-reflective film 113. In some example embodiments, a light shieldingfilter layer 117 is not disposed above an opening area 114 a of thelight shield grid 114, but is instead disposed so as to overlap thelight shield grid 114. In some example embodiments, a transparent layerincluding a transparent material may be disposed in the opening area 114a.

Some example embodiments may prevent or reduce light from beingreflected from the upper surface of the light shield grid 114 byincluding a light shielding filter layer 117 including laminated layers,wherein the laminated layers include at least one of a red color filter,a green color filter, and a blue color filter.

Some example embodiments may include a light shielding filter layer 117including a laminated structure in which two or more laminated layers ofcolor filters are selected from a group comprising a red color filter, agreen color filter, a blue color filter, a cyan color filter, a magentacolor filter, and a yellow color filter. In some example embodiment mayinclude color filters of the light shielding filter layer 117 thatinclude an organic material.

Some example embodiments may include color filters of the lightshielding filter layer 117 that include organic material, which may beone material or a combination of two or more materials selected from agroup consisting of polyacetylene, poly(p-phenylene), polythiophene,poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole,poly(p-phenylenesulfide), poly(p-phenylenevinylene), and polyaniline.

Some example embodiments may include a planarization layer 115 that isdisposed on the light shielding filter layer 117. In some exampleembodiments, an upper surface of the device, on which a lens 116 isdisposed, may be flattened by the planarization layer 115. Some exampleembodiments may include a planarization layer 115 that include ones ormore films selected from the group consisting of an oxide film, anitride film, and an oxynitride film. Some example embodiments mayinclude a planarization layer 115 that includes a plurality of laminatedfilms in which two or more films are selected from the group consistingof the oxide film, the nitride film, and the oxynitride film.

In some example embodiments, light generated in an organic lightemitting diode (OLED) panel 210 may be reflected by a finger of a userand may be incident on each pixel 110 of the image sensor 100. Forexample, light may pass through the lens 116 and/or the planarizationlayer 115, and/or may be incident on the photodiode 112 after passingthrough the anti-reflective film 113 through the opening area 114 a inthe light shield grid 114.

The BSI image sensor 100 of some example embodiments of some inventiveconcepts may prevent or reduce interference between the pixels (e.g.,adjacent pixels) by disposing the DTI between the pixels (e.g., adjacentpixels). In some example embodiments, dark current may be suppressed orreduced by a dark current suppression layer 111 that is disposed abovethe photodiode 112. In some example embodiments, light may be preventedor reduced from being reflected by the anti-reflective film 113 disposedabove the photodiode 112, which may promote light efficiency in someexample embodiments. In some example embodiments, dark current may besuppressed or reduced by disposing a dark current suppression layer 111above the photodiode 112 and applying voltage within a range of 0V to−2V to the light shield grid 114 formed of a metal material.

FIG. 7A is a view illustrating a pixel of an image sensor according tosome example embodiments of some inventive concepts, in which ananti-reflective film is disposed between a light shielding filter layerand a planarization layer. FIG. 7B is a view illustrating a case inwhich a device isolation film is disposed in the pixel shown in FIG. 7Ain accordance with some example embodiments. In describing a pixel 110shown in FIGS. 7A and 7B, description of the same configuration as thepixel 110 shown in FIGS. 3A to 3C may be omitted.

Referring to FIGS. 1 and 7A, some example embodiments may include apixel 110 of a BSI image sensor 100. In some example embodiments, eachof the plurality of pixels 110 may include a dark current suppressionlayer 111, a photodiode 112, a light shield grid 114, a light shieldingfilter layer 117, an anti-reflective film 113, a planarization layer115, and/or a lens 116.

In some example embodiments, during a manufacturing process of the imagesensor 100, a portion of a back side of a silicon substrate may be cutto a thickness in a height direction (for example, 3 μm) through whichlight may be transmitted, and/or the photodiode 112 may be disposed on aback side of the silicon substrate. In some example embodiments,transistors and/or wirings may be disposed on a front side of thesilicon substrate. In some example embodiments, a dark currentsuppression layer 111 may be disposed above the photodiode 112; a lightshield grid 114 may be disposed above the dark current suppression layer111; a light shielding filter layer 117 may be disposed on the lightshield grid 114; an anti-reflective film 113 may be disposed on thelight shielding filter layer 117; a planarization layer 115 may bedisposed on the anti-reflective film 113; and/or a lens 116 may bedisposed on the planarization layer 115.

In some example embodiments, dark current may degrade the performance ofsome image sensors, and it may be necessary, desirable, and/oradvantageous to eliminate, prevent, reduce, and/or suppress darkcurrent. In some example embodiments of some inventive concepts, thedark current suppression layer 111 may be disposed above the photodiode112. In some example embodiments, a dark current suppression layer 111may be disposed on an upper side of the silicon substrate.

As shown in FIG. 7B, in some example embodiments, a deep trenchisolation (DTI) having a certain (e.g., desired and/or selected) depthmay be disposed between some pixels (e.g., between adjacent pixels). Insome example embodiments, a dark current suppression layer 111 may bedisposed above the photodiode 112.

In some example embodiments, a DTI may reduce interference between somepixels (e.g., adjacent pixels) and/or may be disposed to surround eachpixel. Some example embodiments may include a DTI that is formed byforming a trench on a back side of the silicon substrate, and thenburying an insulating film in the trench. Some example embodiments mayinclude a DTI having a depth in a height direction of 1 μm to 5 μm. Insome example embodiments, a DTI may include a deep trench isolationlayer including an insulating material, which may have a refractiveindex that is smaller than the refractive index of the siliconsubstrate, which may prevent or reduce light incident on each pixel frompassing over another adjacent pixel. In some example embodiments,interference of the light between adjacent pixels may be prevented orreduced by forming the DTI deep in a height direction in the substrate.

Some example embodiments may include a DTI that is disposed on a backside of the silicon substrate and/or a dark current suppression layer111 that is disposed above the photodiode 112 and/or the DTI. Someexample embodiments may include a dark current suppression layer 111that is integrally formed with a DTI. Some example embodiments mayinclude a dark current suppression layer 111 that is disposed on a frontside of the silicon substrate. In some example embodiments, dark currentmay be prevented or reduced in the photodiode 112 by applying voltagewithin the range of 0V to −2V to the light shield grid 114 and/or thedark current suppression layer 111.

Some example embodiments may include a dark current suppression layer111 including a plurality of laminated layers respectively having afixed negative charge. In some example embodiments, each layer of theplurality of layers of the dark current suppression layer 111 mayinclude one material or a combination of two or more materials in thegroup including aluminum oxide (AlO), tantalum oxide (TaO), hafniumoxide (HfO), zirconium oxide (ZrO), and lanthanum oxide (LaO).

In some example embodiments, and as shown in FIG. 3C, a dark currentsuppression layer 111 and a DTI may be integrated together and/or mayinclude a plurality of layers. In some example embodiments, a darkcurrent suppression layer 111 and a DTI may be integrally formed bylaminating a plurality of layers, each having a fixed negative charge.Some example embodiments may include an anti-reflective film 113 that isdisposed on the light shielding filter layer 117. That is, in someexample embodiments, an anti-reflective film 113 may be disposed betweenthe light shielding filter layer 117 and the planarization layer 115.

Some example embodiments may include an anti-reflective film 113including a plurality of laminated sub-films, which may prevent and/orreduce the reflection of light. Some example embodiments may include ananti-reflective film 113 including a plurality of sub-films. As shown inFIGS. 4A and 4B, some example embodiments may include an anti-reflectivefilm 113 that includes four sub-films 113 a to 113 d shown. However,some example embodiments of some inventive concepts may not be limitedthereto; for example, some other example embodiments may include ananti-reflective film 113 including 10 to 40 overlapping sub-films. Insome example embodiments, each of the sub-films of the plurality ofsub-films of the anti-reflective film 113 may have a refractive indexthat is different than the refractive indices of other sub-films of theanti-reflective film 113. Some example embodiments of some inventiveconcepts may not be limited thereto; for example, in some other exampleembodiments, some sub-films among the plurality of sub-films of theanti-reflective film 113 may have the same refractive index.

Some example embodiments of some inventive concepts may prevent orreduce the light being reflected from an upper surface of the lightshield grid 114 by including a light shielding filter layer 117 disposedon the light shield grid 114. The light shielding filter layer 117 isnot formed above an opening area 114 a of the light shield grid 114 butmay be disposed so as to overlap the light shield grid 114. Atransparent layer formed of a transparent material may be disposed inthe opening area 114 a.

As one example, in order to prevent the light from being reflected fromthe upper surface of the light shield grid 114, the light shieldingfilter layer 117 may be disposed in a laminated form of a red colorfilter, a green color filter, and a blue color filter.

As one example, the light shielding filter layer 117 may be formed in astructure in which two or more color filters selected from the groupconsisting of the red color filter, the green color filter, the bluecolor filter, a cyan color filter, a magenta color filter, and a yellowcolor filter are laminated. The color filters of the light shieldingfilter layer 117 may be an organic material.

The color filters of the light shielding filter layer 117 may be theorganic material. The organic material that is the material of the colorfilter may be one material or a combination of two or more materialsselected from the group consisting of polyacetylene, poly(p-phenylene),polythiophene, poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole,poly(p-phenylenesulfide), poly(p-phenylenevinylene), and polyaniline.

An upper surface, on which the lens 116 is disposed, may be flattened bythe planarization layer 115. As one example, the planarization layer 115may include one or more films selected from the group consisting of anoxide film, a nitride film, and an oxynitride film. As one example, theplanarization layer 115 may include a plurality of films in which two ormore films selected from the group consisting of the oxide film, thenitride film, and the oxynitride film are laminated.

The light generated in an organic light emitting diode (OLED) panel 210may be reflected by a finger and incident on each pixel 110 of the imagesensor 100. The light passes through the lens 116 and the planarizationlayer 115. Thereafter, the light may be incident on the photodiode 112after passing through the anti-reflective film 113 through the openingarea 114 a formed by the light shield grid 114.

The BSI image sensor 100 of some example embodiments of some inventiveconcepts may prevent or reduce the interference between the pixels bydisposing the DTI between the pixels. The dark current may be suppressedfrom being generated by the dark current suppression layer 111 disposedabove the photodiode 112. The light may be prevented from beingreflected by the anti-reflective film 113 disposed above the photodiode112, so that light efficiency may be improved. Further, dark current maybe suppressed or reduced by disposing the dark current suppression layer111 above the photodiode 112 and applying voltage within a range of 0Vto −2V to the light shield grid 114 formed of a metal material.

FIG. 8A is a view illustrating a pixel of an image sensor according tosome example embodiments of some inventive concepts, in which ananti-reflective film is disposed between a planarization layer and alens. FIG. 8B is a view illustrating a case in which a device isolationfilm is disposed in the pixel shown in FIG. 8A. In describing a pixel110 shown in FIGS. 8A and 8B, description of the same configuration asthe pixel 110 shown in FIGS. 3A to 3C may be omitted.

Referring to FIGS. 1 and 8A, the pixel 110 of a BSI image sensor 100 inaccordance with some example embodiments is shown. Some exampleembodiments may include an a plurality of pixels 110, each including adark current suppression layer 111, a photodiode 112, a light shieldgrid 114, a light shielding filter layer 117, a planarization layer 115,an anti-reflective film 113, and/or a lens 116.

In some example embodiments, during a manufacturing process of an imagesensor 100, a portion of a back side of a silicon substrate may be cutto a thickness in a height direction (for example, 3 μm) through whichlight may be transmitted, and/or a photodiode 112 may be formed on aback side of the silicon substrate. Some example embodiments may includetransistors and/or wirings are formed on a front side of the siliconsubstrate. Some example embodiments may include a dark currentsuppression layer 111 disposed above a photodiode 112; a light shieldgrid 114 that is disposed above the dark current suppression layer 111;a light shielding filter layer 117 that is disposed on the light shieldgrid 114; a planarization layer 115 that is disposed on the lightshielding filter layer 117; an anti-reflective film 113 that is disposedon the planarization layer 115; and/or a lens 116 that is disposed onthe anti-reflective film 113.

In some example embodiments, dark current may degrade the performance ofsome image sensors, and it may be necessary, desirable, and/oradvantageous to eliminate, prevent, reduce, and/or suppress darkcurrent. In some example embodiments of some inventive concepts, thedark current suppression layer 111 may be disposed above the photodiode112. Some example embodiments may include a dark current suppressionlayer 111 disposed on an upper side of the silicon substrate

As shown in FIG. 8B, some example embodiments may include a deep trenchisolation (DTI) having a certain (e.g., desired and/or selected) depthand disposed between some pixels (e.g., between adjacent pixels). Someexample embodiments may include a dark current suppression layer 111disposed above a photodiode 112.

Some example embodiments may include a DTI that prevents or reduceinterference between the pixels and may be disposed to surround eachpixel. Some example embodiments may include a DTI that is formed byforming a trench on a back side of the silicon substrate and thenburying an insulating film in the trench. Some example embodiments mayinclude a DTI that has a depth of 1 μm to 5 μm in a height direction.Some example embodiments may include a DTI that includes a deep trenchisolation layer including an insulating material. Some exampleembodiments may include a DTI including an insulating material having arefractive index that is smaller than the refractive index of thesilicon substrate, which may prevent and/or reduce light incident oneach pixel from passing over another adjacent pixel. In some exampleembodiments, interference of the light between adjacent pixels may beprevented or reduced by forming the DTI deep in a height direction inthe substrate.

Some example embodiments may include a DTI that is disposed on a backside of the silicon substrate and/or a dark current suppression layer111 that is disposed above a photodiode 112 and/or the DTI. Some exampleembodiments may include a dark current suppression layer 111 may that isintegrally formed with the DTI. Some example embodiments may include adark current suppression layer 111 that is formed on a front side of thesilicon substrate. Some example embodiments may be configured to preventand/or reduce dark current in the photodiode 112 by applying voltagewithin a range of 0V to −2V to the light shield grid 114 and/or the darkcurrent suppression layer 111.

Some example embodiments may include a dark current suppression layer111 including a plurality of laminated layers, each having a fixednegative charge. Some example embodiments may include a dark currentsuppression layer 111 including a plurality of layers, each includingone or more materials or a combination of two or more materials in thegroup including aluminum oxide (AlO), tantalum oxide (TaO), hafniumoxide (HfO), zirconium oxide (ZrO), and lanthanum oxide (LaO).

As shown in FIG. 3C, some example embodiments may include a dark currentsuppression layer 111 and a DTI that are integrated together and formedof a plurality of layers. In some example embodiments, the dark currentsuppression layer 111 and the DTI may be integrally formed by laminatinga plurality of layers, each having a fixed negative charge.

Some example embodiments of some inventive concepts may prevent orreduce the light being reflected from an upper surface of the lightshield grid 114 by a light shielding filter layer 117 disposed on alight shield grid 114. In some example embodiments, the light shieldingfilter layer 117 is not disposed above an opening area 114 a of thelight shield grid 114, but may be disposed so as to overlap the lightshield grid 114. Some example embodiments may include an opening area114 a including a transparent layer including a transparent material.

Some example embodiments may prevent or reduce light from beingreflected from the upper surface of the light shield grid 114 byincluding a light shielding filter layer 117 in a laminated form of ared color filter, a green color filter, and a blue color filter.

Some example embodiments may include a light shielding filter layer 117including a structure of laminated color filters, including two or morecolor filters that are selected from the group comprising a red colorfilter, a green color filter, a blue color filter, a cyan color filter,a magenta color filter, and a yellow color filter. In some exampleembodiments, the color filters of the light shielding filter layer 117may include an organic material.

Some example embodiments may include color filters of a light shieldingfilter layer 117 that include an organic material, which may be onematerial or a combination of two or more materials selected from thegroup consisting of polyacetylene, poly(p-phenylene), polythiophene,poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole,poly(p-phenylenesulfide), poly(p-phenylenevinylene), and polyaniline.

Some example embodiments may include a planarization layer 115 thatincludes one or more films selected from the group consisting of anoxide film, a nitride film, and an oxynitride film. Some exampleembodiments may include a, planarization layer 115 including a pluralityof films in which two or more films selected from the group consistingof the oxide film, the nitride film, and the oxynitride film arelaminated.

Some example embodiments may include an anti-reflective film 113 that isdisposed on a planarization layer 115. That is, some example embodimentsmay include an anti-reflective film 113 disposed between a planarizationlayer 115 and a lens 116.

Some example embodiments may include an anti-reflective film 113including a plurality of laminated sub-films, which may prevent and/orreduce a reflection of light. Some example embodiments may include ananti-reflective film 113 that includes a plurality of sub-films. Asshown in FIGS. 4A and 4B, some example embodiments may include ananti-reflective film 113 including four sub-films 113 a to 113 d.However, some example embodiments of some inventive concepts may not belimited thereto; for example, some other example embodiments may includean anti-reflective film 113 including 10 to 40 overlapping sub-films. Insome example embodiments, each sub-film the plurality of sub-films ofthe anti-reflective film 113 may have a refractive index that isdifferent than the refractive indices of other sub-films of theanti-reflective film 113. Some example embodiments of some inventiveconcepts may not be limited thereto; for example, in some other exampleembodiments, some sub-films among the plurality of sub-films of theanti-reflective film 113 may have a same or similar refractive index asother sub-films of the anti-reflective film 113.

In some example embodiments, light generated in an organic lightemitting diode (OLED) panel 210 may be reflected by a finger of a userand may be incident on each pixel 110 of the image sensor 100. In someexample embodiments, the light reflected by the finger may pass througha lens 116, an anti-reflective film 113, and/or a planarization layer115 and/or may be incident on a photodiode 112 through an opening area114 a formed by a light shield grid 114.

The BSI image sensor 100 of some example embodiments of some inventiveconcepts may prevent or reduce interference between the pixels bydisposing the DTI between some pixels (e.g., adjacent pixels). In someexample embodiments, dark current may be suppressed or reduced by a darkcurrent suppression layer 111 disposed above the photodiode 112. In someexample embodiments, reflection of light may be prevented or reduced byan anti-reflective film 113 disposed above the photodiode 112, which maypromote light efficiency in some example embodiments. In some exampleembodiments, dark current may be suppressed or reduced by disposing adark current suppression layer 111 above the photodiode 112 and applyingvoltage within a range of 0V to −2V to the light shield grid 114 formedof a metal material.

In some example embodiments of some inventive concepts, interferencebetween pixels may be prevented or reduced in a narrow inter-pixelstructure, and thus a clear fingerprint image may be generated.

In some example embodiments of some inventive concepts, influence onsensitivity due to wirings may be excluded or reduced by disposing thewirings under a photodiode.

In some example embodiments of some inventive concepts, interferencebetween pixels may be prevented or reduced by disposing a deep trenchisolation (DTI) between the pixels.

In some example embodiments of some inventive concepts, a dark currentof a photodiode may be reduced by disposing a dark current suppressionlayer above the photodiode.

In some example embodiments of some inventive concepts, sensingsensitivity of a photodiode may be increased by disposing ananti-reflective film above the photodiode.

In some example embodiments of some inventive concepts, dark current maybe suppressed or reduced by applying voltage within a range of 0 V to −2V to a light shield grid formed of a metal material

While some example embodiments of some inventive concepts have beendescribed with reference to the accompanying drawings, variousmodifications may be made without departing from the scope of thepresent disclosure. Therefore, the above-described embodiments should beconsidered in a descriptive sense only and not for purposes oflimitation.

What is claimed is:
 1. An image sensor comprising: a substrate; aphotodiode in the substrate; a light shield grid on the photodiode; alight shielding filter layer formed above the light shield grid, thelight shielding filter layer including an opening above the photodiode;a planarization layer formed above the light shielding filter layer; andan anti-reflection film, including a plurality of sub-films on andplanar to the planarization layer; wherein the plurality of sub-filmscomprises a stack including at least a first sub-film and a secondsub-film.
 2. The image sensor of claim 1, wherein the first sub-film hasa first refractive index and the second sub-film has a second refractiveindex different from the first refractive index.
 3. The image sensor ofclaim 1, wherein a thickness of the first sub-film and a thickness ofthe second sub-film are different.
 4. The image sensor of claim 1,wherein each of a thickness of the first sub-film and a thickness of thesecond sub-film is within 0.1 μm-0.5 μm.
 5. The image sensor of claim 1,wherein the stack further comprise third to tenth sub-films on thesecond sub-film.
 6. The image sensor of claim 5, wherein at least two ofthe first to tenth sub-films have a same refractive index.
 7. The imagesensor of claim 1, wherein the plurality of sub-films include aplurality of low refractive index films and a plurality of highrefractive index films alternately laminated on the plurality of lowrefractive index films.
 8. The image sensor of claim 7, wherein each ofhigh refractive index films has a refractive index within a range of 2.0to 2.8.
 9. The image sensor of claim 7, wherein each of low refractiveindex films has a refractive index within a range of 1.2 to 1.8.
 10. Theimage sensor of claim 1, wherein the plurality of sub-films include 10to 40 sub-films.
 11. An electronic device including image sensor, theimage sensor comprising: a substrate; a photodiode in the substrate; alight shield grid on the photodiode; a light shielding filter layerformed above the light shield grid, the light shielding filter layerincluding an opening above the photodiode; a planarization layer formedabove the light shielding filter layer; an anti-reflection layer,including a plurality of sub-films on and planar to the planarizationlayer; and an organic light emitting diode panel on the plurality ofsub-films; wherein the plurality of sub-films comprises a stackincluding at least a first sub-film and a second sub-film.
 12. Theelectronic device of claim 11, wherein the first sub-film has a firstrefractive index and the second sub-film has a second refractive indexdifferent from the first refractive index.
 13. The electronic device ofclaim 11, wherein a thickness of the first sub-film and a thickness ofthe second sub-film are different.
 14. The electronic device of claim11, wherein each of a thickness of the first sub-film and a thickness ofthe second sub-film is within 0.1 μm-0.5 μm.
 15. The electronic deviceof claim 11, wherein the stack further comprise third to tenth sub-filmson the second sub-film.
 16. The electronic device of claim 15, whereinat least two of the first to tenth sub-films have a same refractiveindex.
 17. The electronic device of claim 11, wherein the plurality ofsub-films include a plurality of low refractive index films and aplurality of high refractive index films alternately laminated on theplurality of low refractive index films.
 18. The electronic device ofclaim 17, wherein each of high refractive index films has a refractiveindex within a range of 2.0 to 2.8.
 19. The electronic device of claim17, wherein each of low refractive index films has a refractive indexwithin a range of 1.2 to 1.8.
 20. The electronic device of claim 17,further comprising a touch panel on the organic light emitting diodepanel.